Pseudo film coefficient of ambient fluid at ground level

When a pipe is fully buried, a term, the pseudo film coefficient, $h_{amb}$, is modeling the heat transfer by convection at the sea/soil interface.

Symbol
$h_{amb}$
Unit
W/(K.m$^2$)
Formulae
$\frac{D_{ext} h_{ext}}{D_{soil}}$Carslaw & Jaeger
$\frac{D_{ext} h_{ext}}{D_{ref}}$Morud & Simonsen / Ovuworie / OTC 23033
$\frac{k_{w} wNu_{w}}{D_{soil}}$fully buried
Related
$D_{ext}$
$h_{ext}$
Used in
$\mathrm{Bi}_{g}$
$U_{buried}$